BASEL, Switzerland—ArtInfo has learned that New York modern and Post-War collector David Martinez is the proud new owner of Willem de Kooning's magisterial Untitled XII from 1976 that sold on Tuesday at PaceWildenstein's stand for approximately $15 million.

A source told us that uber-designer and advisor Peter Marino inspected the painting and measured it for his client, Martinez, a Mexican-born financial magnate who resides in New York City.

Remarkably, when the painting was first exhibited at the long shuttered Sidney Janis Gallery in New York, it carried a price tag of $60,000 and remained unsold for a time, according to a knowledgeable source.